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Universal Heliar - Soft focus mechanism servicing

My, almost completely seized up, Universal Heliar has come back to me to-day. I promised, a long time ago, to have a go at fixing this problem and post photos and description. I understand there are a number of owners who have similar, if quite not so acute, problems.

This is also of relevance for cleaning the inside middle bi-concave lens and the insides of the other lenses.

I think that Voigtländer has changed the location of the only lock screw during the long life of the Universal. Tim Deming mentioned that his was hidden underneath the broad aperture ring. Mine wasn't - it was only screw in the side of the barrel in front of the aperture ring.
I should also explain that mine is a pre-Universal engraved type - before Voigtländer decided on the Universal name. I have no reason to believe that the mechanism was changed when they decided to make it a standard product.

I would label this a ** level difficulty job.
** means that it can done on a kitchen table with good lighting with ordinary tools at one session. Knowledge of clockwise/anticlockwise is required as well as a container (soup dish?) for the 3 small screws and a soft cover to the table. The Heliar is very well put together and the problem with friction in the turning system doesn't mean that the screws are going to be difficult. Remember this one is older than almost everyone else's Heliar!
The first photo shows Heliar. The second shows the aperture ring removed (just a single screw which goes down to a rather concealed hole/thread in the aperture disc) and the locking screw (central in the photo) for the front/lens assembly. Note that this screw is fortunately steel - otherwise we would have a rash of total failures with severed brass screws. When this is removed, the front assembly can be unscrewed from the front -the last photo.

Re: Universal Heliar - Soft focus mechanism servicing

The front drive of the middle lens of the Heliar is provided by 3 angled slots cut out of a brass barrel. I suppose it is 3 to maintain the centre position of the inner, shorter, barrel which is the mount for the central lens. The system is exactly the same, but with better engineering, as the method used with projection lenses. These slots provide much more movement than the 0 to 5 soft marking on the front rim indicate. The movement is restricted by a short slot and a screw. This screw has to be removed and this allows the friction surfaces/diagonal slots to be accessed. Photo 1 shows this restricting slot.
The following photos show the various components when the outer barrel is pulled off.

Re: Universal Heliar - Soft focus mechanism servicing

The inner tube can now be moved to both extremes of the long diagonal slots - well beyound the usual movement allowed. The two barrels can be totally separated by removing the two screws holding each of the three sliders. I don't recommend doing this unless absolutely necessary. Each of these has a separate stamp *,** and ***, matching a similar mark on the barrel. This reminds me of the stamping marks on engine bearings which are marked in the same way - indicating the correct pairing. The fact that the screws have perfectly alligned head slots is also a danger signal.
I am sure that this could be done - but the following method seems to work OK without taking the risk.
I cleaned the visable hardened grease off and then applied small quantities of terpentine around the edge and repeatedly moved the barrel in and out. The semi dissolved grease was removed from the edge and the 3 lots. This was repeated for 30 minutes with the turning ceming easier and easier. It is obvious that there is/has been metal to metal contact as there are scratch marks in the visable area which follow exactly the oblique movement of the outer barrel. The barrels were left to dry in a warm place. New grease (very little) was applied at the edge of the overlap and down in the slots. After copious in and out movements, the excess grease which hadn't been forced into the working area, was removed.
Assembly was extremely easy. Locating the fixing hole for the soft focussing adjustment is easy. The thread for the iris ring cannot been seen when the iris ring is in place (too deep too dark), so the exact location of the hole must noted on the aperture scale before the ring is put back on.
I forgot to mention that the middle lens can be removed using a standard lens wrench.
I have also posted a photo of the rubbish that was removed from this operation.

Re: Universal Heliar - Soft focus mechanism servicing

A few afterthoughts!

- Do not dispair if the weakest point in the mechanism - the single small steel screw has sheared off. There is plenty of clearance inside for the end of a new, slightly larger screw and thread. And the machining is on items which can be separated from the glass.
- I used quite heavy grease, although I was tempted to use lighter fractions of lubricant. The adjustment is a hand adjustment process - not a finger activity. Lighter lubricants might have made it easier, but there is a greater risk of lubricant "drip" and solvent condensates on the, rather difficult to get at, inner surfaces.

Re: Universal Heliar - Soft focus mechanism servicing

A final note!

My Heliar needed "handles" which have been (well) made by Grimes. The existing threads on the rim turned out to be M2.5 rather than the standard M3. So I have cut new M3 threads.
The handles give an opportunity to measure the effort needed to turn the soft focus ring, which may help others to diagnose their own Universals. Easy, OK and stiff can mean many things!
I placed my fishing spring balance on one of the handles and measured the pull required to turn it in both directions.
Starting moment was around 3 kilos and the rotation continued with just 2 kilos.
I would be interested in hearing what others measure this too?